]>
Commit | Line | Data |
---|---|---|
b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
f405df5d PZ |
2 | #ifndef _LINUX_REFCOUNT_H |
3 | #define _LINUX_REFCOUNT_H | |
4 | ||
f405df5d | 5 | #include <linux/atomic.h> |
f405df5d PZ |
6 | #include <linux/mutex.h> |
7 | #include <linux/spinlock.h> | |
318b1ded | 8 | #include <linux/kernel.h> |
f405df5d | 9 | |
bd174169 DW |
10 | /** |
11 | * refcount_t - variant of atomic_t specialized for reference counts | |
12 | * @refs: atomic_t counter field | |
13 | * | |
14 | * The counter saturates at UINT_MAX and will not move once | |
15 | * there. This avoids wrapping the counter and causing 'spurious' | |
16 | * use-after-free bugs. | |
17 | */ | |
f405df5d PZ |
18 | typedef struct refcount_struct { |
19 | atomic_t refs; | |
20 | } refcount_t; | |
21 | ||
22 | #define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), } | |
23 | ||
bd174169 DW |
24 | /** |
25 | * refcount_set - set a refcount's value | |
26 | * @r: the refcount | |
27 | * @n: value to which the refcount will be set | |
28 | */ | |
f405df5d PZ |
29 | static inline void refcount_set(refcount_t *r, unsigned int n) |
30 | { | |
31 | atomic_set(&r->refs, n); | |
32 | } | |
33 | ||
bd174169 DW |
34 | /** |
35 | * refcount_read - get a refcount's value | |
36 | * @r: the refcount | |
37 | * | |
38 | * Return: the refcount's value | |
39 | */ | |
f405df5d PZ |
40 | static inline unsigned int refcount_read(const refcount_t *r) |
41 | { | |
42 | return atomic_read(&r->refs); | |
43 | } | |
44 | ||
fd25d19f | 45 | #ifdef CONFIG_REFCOUNT_FULL |
29dee3c0 PZ |
46 | extern __must_check bool refcount_add_not_zero(unsigned int i, refcount_t *r); |
47 | extern void refcount_add(unsigned int i, refcount_t *r); | |
f405df5d | 48 | |
29dee3c0 PZ |
49 | extern __must_check bool refcount_inc_not_zero(refcount_t *r); |
50 | extern void refcount_inc(refcount_t *r); | |
f405df5d | 51 | |
29dee3c0 | 52 | extern __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r); |
f405df5d | 53 | |
29dee3c0 PZ |
54 | extern __must_check bool refcount_dec_and_test(refcount_t *r); |
55 | extern void refcount_dec(refcount_t *r); | |
fd25d19f | 56 | #else |
7a46ec0e KC |
57 | # ifdef CONFIG_ARCH_HAS_REFCOUNT |
58 | # include <asm/refcount.h> | |
59 | # else | |
fd25d19f KC |
60 | static inline __must_check bool refcount_add_not_zero(unsigned int i, refcount_t *r) |
61 | { | |
62 | return atomic_add_unless(&r->refs, i, 0); | |
63 | } | |
64 | ||
65 | static inline void refcount_add(unsigned int i, refcount_t *r) | |
66 | { | |
67 | atomic_add(i, &r->refs); | |
68 | } | |
69 | ||
70 | static inline __must_check bool refcount_inc_not_zero(refcount_t *r) | |
71 | { | |
72 | return atomic_add_unless(&r->refs, 1, 0); | |
73 | } | |
74 | ||
75 | static inline void refcount_inc(refcount_t *r) | |
76 | { | |
77 | atomic_inc(&r->refs); | |
78 | } | |
79 | ||
80 | static inline __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r) | |
81 | { | |
82 | return atomic_sub_and_test(i, &r->refs); | |
83 | } | |
84 | ||
fd25d19f KC |
85 | static inline __must_check bool refcount_dec_and_test(refcount_t *r) |
86 | { | |
87 | return atomic_dec_and_test(&r->refs); | |
88 | } | |
89 | ||
90 | static inline void refcount_dec(refcount_t *r) | |
91 | { | |
92 | atomic_dec(&r->refs); | |
93 | } | |
7a46ec0e | 94 | # endif /* !CONFIG_ARCH_HAS_REFCOUNT */ |
fd25d19f | 95 | #endif /* CONFIG_REFCOUNT_FULL */ |
f405df5d | 96 | |
29dee3c0 PZ |
97 | extern __must_check bool refcount_dec_if_one(refcount_t *r); |
98 | extern __must_check bool refcount_dec_not_one(refcount_t *r); | |
99 | extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock); | |
100 | extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock); | |
f405df5d PZ |
101 | |
102 | #endif /* _LINUX_REFCOUNT_H */ |